CN1977498A

CN1977498A - Wireless sensor network

Info

Publication number: CN1977498A
Application number: CNA2005800088331A
Authority: CN
Inventors: 理查德·费里; 金文柱; 余德材
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 2004-05-28
Filing date: 2005-05-18
Publication date: 2007-06-06
Anticipated expiration: 2025-05-18
Also published as: KR100951252B1; TWI341113B; CA2568576A1; IL179596A0; JP2008501263A; EP1757043A1; US20090002151A1; TW200627872A; US7475158B2; BRPI0511585B1; CN1977498B; WO2005119981A1; KR20070038952A; JP4750109B2; US8041834B2; IL179596A; AU2005251009A1; US20050275532A1; BRPI0511585A

Abstract

A system and method for implementing a wireless sensor network. The system comprises a plurality of motes, each mote having a sensor and a wireless communication system for communicating with neighboring motes; a distributed routing table distributed amongst each of the plurality of motes; and an update system for periodically updating the distributed routing table. The method comprises broadcasting a joint command from each mote and a gather command from an endpoint.

Description

Wireless sensor network

Technical field

The present invention relates to wireless sensor network, relate in particular to the system that transmits the monitoring of information environmental change with the peer-to-peer network architecture.

Background technology

Today, exist many public safety hazards, such as brush fires, biochemical accident or invasion and attack etc. based on environment.Obtaining real-time information with accurate relevant this danger is critical for preventing dangerous and minimum being reduced in loss.

Two anxious widely problems to be solved handling this danger are: (1) is in time at place, adventurous place acquired information; And (2) send information to monitoring station reliably.Unsatisfactory for being extensive use of current solution such as the satellite imagery of acquired information or the heat sensor, because their costs are high and effective inadequately.Usually, the data that produce with current transducer solution are uncertain, and produce in post incident.Therefore, can not rely on this data and in time make how handling dangerous decision-making.

It also is uncertain transmitting the information that transducer gathers, because be used for transmitting the influence that the communication channel of data may be subjected to accident.That is to say that if there is critical communication node to break down in the sensor network, critical information just can not obtain analyzing, thereby can not in time take measures according to this information.

The current example that has many sensor-based detection systems.United States Patent (USP) 6,169,476 B1 " Early Warning System forNatural and Manmade Disasters " that for example authorize Flanagan January 2 calendar year 2001 have disclosed a kind of system that produces early warning signal by network.Authorize the United States Patent (USP) 6 of Berry September 25 calendar year 2001,293,861B1 " Automatic Response Building Defense System and Method " has disclosed a kind of system that detects near the noxious pollutant of building and take some automation measure.More than two patents classify as with reference to being quoted at this.Unfortunately, these prior aries all also do not disclose a kind of firm wireless sensing system, can with economical and reliably mode obtain and transmit institute's sensed data.Therefore, be necessary to develop such system.

Summary of the invention

The preferred embodiments of the present invention have been considered above-mentioned and some other problem, a kind of wireless sensor network is provided, this wireless sensor network utilize " SMART DUST " transducer in other words " micronic dust (mote) " come the variation of testing environment and by grid (mesh) or self-organizing network broadcast transmission of data.Each micronic dust comprises the environmental change power supply (for example, solar cell), network node (for example, remote transceiver) and the spike of energy measurement in temperature and detects the microdevice (that is transducer) of hazardous chemical article.The transmission of key data is not provide the grid of communication or self-organizing network to realize by relying on a single point.If transducer damages or becomes and can't use, the transducer of another work can continue transmission so.By realize the elasticity of network by the virtual map logo available sensors of self-organizing network.

The present invention provides a kind of wireless sensor network from first aspect, and this wireless sensor network comprises: a plurality of micronic dusts, each micronic dust have transducer and the wireless communication system of communicating by letter with neighbor micronic dust; Be distributed in the distributed routing table between each micronic dust in a plurality of micronic dusts; And the update system of distributed routing table termly.

The present invention is from second aspect, a kind of method that realizes having the wireless sensor network of a plurality of micronic dusts is provided, each micronic dust has transducer and the wireless communication system of communicating by letter with neighbor micronic dust, and described method comprises the following steps: to add order and collect order from end points broadcasting from each micronic dust broadcasting; Utilize end points to make the equipment adjacent add network with end points; Collect signal from each the micronic dust broadcasting that adds end points, so that other micronic dusts add network; Collect signal from each other micronic dust broadcasting that adds network, make more other micronic dusts add network.This method can also comprise the broadcasting step that repetition is previous, can add network up to no longer including more micronic dust.

The present invention provides a kind of micronic dust that is used for sensor network from the third aspect, and this micronic dust comprises: the transducer of sensitive context data; The communication system of communicating by letter with neighbor micronic dust; Micronic dust is built up in adding and gathering system in the mote network; The routing table of one group of path of end points is returned in arrangement (rank) from micronic dust; And the update system of upgrading routing table termly.

The present invention is from fourth aspect, a kind of method that realizes having the wireless network of a plurality of equipment is provided, each equipment has the wireless communication system of communicating by letter with neighbouring device, and described method comprises the following steps: to add order and collect order from end points broadcasting from each device broadcasts; Utilize end points to make the equipment adjacent add network with end points; Collect signal from each device broadcasts that adds end points, so that other equipment add network; And from adding each other device broadcasts collection signal of network, so that more other equipment add networks.

Description of drawings

Illustratively the preferred embodiments of the present invention are described below in conjunction with accompanying drawing, in these accompanying drawings:

Fig. 1 shows wireless sensor network designed according to this invention;

Fig. 2 shows a plurality of designed according to this invention micronic dusts;

Fig. 3 shows the schematic diagram of the routing table update/foundation of mote network; And

Fig. 4 shows the schematic diagram of data by the mote network passback of Fig. 2.

Embodiment

Refer now to these accompanying drawings, wherein Fig. 1 shows wireless sensor network 10, and it comprises mote network 12, one or more transmission router one 6,18,20 and one or more monitoring station 22.Mote network 12 comprises: (1) a plurality of sensitive context change and transmit the micronic dust 13 of data, and (2) provide communications infrastructure, the virtual network 14 of route data between a plurality of micronic dusts 13 by grid or self-organizing network.As following will further specifying, each micronic dust is an energy and independence (self-contained) unit of neighbor micronic dust radio communication.In addition, virtual network 14 comprises the distributed route Figure 15 that is distributed between the micronic dust 13 by update system 17 regular updates.Therefore, if micronic dust has lost the ability of relaying (relay) data, data can use other available micronic dusts to re-route, thereby the elasticity of network is provided.In an exemplary embodiments, " pre-heartbeat (the pre-heartbeat) " algorithm that also will describe in detail below update system 17 is utilized upgrades distributed route Figure 15.

Transmit router one 6,18,20 can comprise can be between mote network 12 and monitoring station 22 router of any kind of relay data.Example has high power cell tower, radio transmitter, microwave transmitter etc.Monitoring station 22 can comprise can to analyze from the sense data of mote network 22, store, the facility of any kind of demonstration etc.

Mote network 12 can realize in a self-organizing that comprises complete grid or part mesh topology or grid network.In complete mesh topology, each micronic dust communicates each other.In the part mesh topology, each micronic dust is not necessarily communicated by letter with other micronic dusts.Though the present invention is described as realizing in wireless environment, is appreciated that some or all of communications also can realize with cable technology.

Refer now to Fig. 2, there is shown a plurality of

micronic dusts

24,40,42,44, wherein at length show micronic dust 24.In this il-lustrative example, micronic dust 24 comprises the sensor layer 28 of the environmental change of for example vibration of microcontroller 26, sensing, wind-force, chemical substance and temperature and so on, the transport network layer 30 with passive layer 32 and active layers 34 and the energy (being solar cell in this case) 36.

The function of microcontroller 26 can comprise: the overall tasks that control is carried out by micronic dust 24 (for example, dispatch sensor reading and communicate by letter) is controlled to be each assembly power supply, handle institute's sensed data, determine the state of micronic dust 24, safeguard and upgrade distributed route Figure 15, or the like.Sensor layer 28 can comprise any kind measurement some comprise the transducer of physics, chemistry or the biological environmental stimulus that changes.Institute's sensed data can be gathered, handles and be stored to sensor layer 28.Transport network layer 30 can comprise the wireless communication system of any kind that permission micronic dust 24 is communicated by letter with

neighbor micronic dust

40,42,44 and/or transmission router four 6.

As noted, each micronic dust comprises passive layer 32 and active layers 34.Passive layer 32 is used for and will (hop) gives another micronic dust from the data passes of a micronic dust or " redirect ".Active layers 34 is used for transmitting the data that micronic dust itself is gathered or produced.Therefore, in this exemplary embodiments, can be directly passed to potentially from the data of micronic dust 24 and to transmit router four 6, jump to by micronic dust 44 and transmit router four 6, perhaps pass to again by

micronic dust

40,42 and 44 redirects earlier and transmit router four 6.Become when unavailable at micronic dust 42, data for example can be from micronic dust 40 (through dotted line) to micronic dust 44 re-route.

As following also to describe in detail, each micronic dust comprise allow micronic dust by neighbor micronic dust " adding " network with make micronic dust its neighbor micronic dust " collection " be gone into the adding and the gathering system 31 of network.The operational capacity of neighbor micronic dust comprises the communication routing iinformation, is kept in the routing table 33.

Fig. 1 again, in order to ensure the micronic dust in the mote network 12 13 can relayings from their information that each attached sensors collected, they must depend on the communication path by neighbor micronic dust strongly.These paths are determined according to the distributed route Figure 15 by update system 17 regular updates.Distributed route Figure 15 is embodied in the routing table that each micronic dust 13 stored.These routing tables are to use arranges possible route path for each micronic dust and creates with " pre-active heartbeat " algorithm that the data relaying is returned main monitoring station.

As noted above, " pre-active heartbeat " algorithm is used for upgrading the routing table of each micronic dust in the mote network 12.In order to finish this task, this algorithm makes micronic dust that their neighbor micronic dust is collected into network 12, makes these neighbor micronic dust collect their neighbor micronic dust again, or the like, all be collected up to all micronic dusts.This process is since an end points, and outwards expands along mote network 12.After, from micronic dust 13 pick-up transducers data the time, the data of being gathered send it back end points.End points for example can comprise simply can with the micronic dust of the specific type that transmits router communication.Each micronic dust can be communicated by letter with one or more neighbor micronic dust.It should be noted, though process is in conjunction with realizing that mote network 12 illustrates that this method can be used to realize using for example network of any kind of the communication equipment of any kinds such as cellular telephone, wireless router, PDA.

When a micronic dust obtained powering first, its communication was limited to the JOIN broadcast, was basically to show " I am ready to add network ".Therefore, when a mote network was started working, each micronic dust can only be broadcasted JOIN, and can not receive response before having end points to get involved.The ability initialization of end points in response to JOIN broadcasting.That is to say that end points will respond with GATHER and reply detected all JOIN broadcasting of its energy.Therefore, end points identification is broadcasted from the JOIN of neighbor micronic dust, and responds with GATHER.In case micronic dust identifies GATHER, this micronic dust just becomes the member of network and the JOIN that goes off the air.Therefore, initial, mote network comprises the neighbor micronic dust of end points and end points.Neighbor micronic dust for example can be defined as the set of the micronic dust that can intercom mutually.

In case micronic dust will itself be established in network, this micronic dust just switches to GATHER broadcasting, to collect its neighbor micronic dust.Like this, constantly circulation, the result is that the micronic dust of each broadcasting JOIN is collected as the neighbor micronic dust of another contiguous collection micronic dust (or saying end points).And when a micronic dust became neighbor micronic dust in the network, it just switched to GATHER from JOIN.Very fast, all micronic dusts all will become the neighbor micronic dust of another micronic dust.In case micronic dust becomes neighbor micronic dust, it is with regard to the energy image data and send it to a neighbor micronic dust.This neighbor micronic dust sends these data to its neighbor micronic dust again, or the like, get back to end points up to data along the road.By making each micronic dust in network, have a plurality of neighbor micronic dust to produce network redundancy in following illustrated mode.

After one very short period, the whole mesh network network has just been set up.Simultaneously, when micronic dust no longer received the JOIN request, micronic dust just can determine that network forms.Each micronic dust will still send GATHER, but frequency is much lower, because the new micronic dust that may add is the micronic dust that for example will replace damaged micronic dust.

Referring now to Fig. 3,, there is shown a mote network, each node is represented a micronic dust, and nodes X is represented end points." pre-active heartbeat " algorithm has two stages basically, and one is the initial phase of setting up grid network, and one is to be updated to the route of end points or the update stage of path.In this il-lustrative example, initial phase begins from the end points in nodes X, starts GATHER process to its neighbor micronic dust (shown in the arrow that stretches out from nodes X among Fig. 3), to begin to form network.In this case, the neighbor micronic dust of nodes X is node W, S and Y.Then, node W, S and Y switch to the collection mode of the neighbor micronic dust of collecting them.Like this, node S collects the second group of neighbor micronic dust that comprises node N, R and T.(notice that this algorithm to the number of possible adjacent node without limits, and is shown just with the reference of this algorithm that lays down a definition.) this process will proceed in network JOIN/GATHER process never again always.

Whenever a node is collected, node and route data that this node that is collected just will be collected its node store, and make each node can both set up a main road that returns end points by path.Like this, as shown in Figure 4, node A will form main road by path A-B-G-H-M-N-S-X.Though this may not be most effective route, this moment is in fact also not serious, in case because network is set up, just can return the path of end points with other method optimizations.Importantly each micronic dust know the main road that returns end points by, and this route is set up by the micronic dust of collecting it and going into network.

As noted above, in case a micronic dust is collected into network, this micronic dust that is collected will remember to return the primary path of end points.Yet,, therefore preferably set up the higher auxilliary path of efficient as the part of initial phase because primary path may not be a path efficiently.The implication of auxilliary path is that other paths that return end points for example are provided under the situation of somewhere micronic dust fault in primary path.In order to set up auxilliary path, each micronic dust will be searched other neighbor micronic dust in the sphere of action that is in it by for example sending simple ping, and preserve the tabulation of showing all this micronic dusts in its sphere of action.

As the part of update stage, each micronic dust sends test packet to these other neighbor micronic dust termly, and writes down various communication criteria, and for example test packet needs how long just to be received.Then, share these data by making each micronic dust and its neighbor micronic dust, micronic dust just can be determined and preserve the tabulation of showing the micronic dust that the most effective path that leads to end points is provided.Each path is stored in the routing table 31 by micronic dust.Therefore, be rendered as when higher than the path efficient by micronic dust y at the path by micronic dust x, micronic dust just is placed on micronic dust x the foremost of tabulation, to be used to send back end points.Like this, micronic dust will be set up primary path (via the micronic dust that gathers it into neighborhood at first) and one group of auxilliary path via contiguous micronic dust that leads to end points.Which mote path micronic dust will assess often is to return the fastest path of end points, thus the highest path of efficiency of selection.

Therefore, " pre-active heartbeat " algorithm guarantees that each micronic dust will have and is used for sending to its end points the optimization routing table of data.Therefore, this will guarantee that used communication path is the most effective and reliable.In addition, it also provides route stand-by, thereby guarantees to send the data to end points safely.

As the part of update stage, its neighbor micronic dust will be checked and assess to each micronic dust, arrange its neighbor micronic dust in routing table.In an exemplary embodiments, the evaluation process prediction is the link-quality when its neighbor micronic dust is transmitted in future.This can realize by retrieving the following factor from each neighbor micronic dust:

1. statistical measurement neighbor micronic dust link (L)

2. estimate path loss (P)

3. estimate the data transfer rate (D) supported

4. estimate transmitting power (TP)

After retrieving these values from its neighbor micronic dust, just can set up a routing table, will provide best communication path to determine which micronic dust.For example, the value from the neighbor micronic dust of the node H in Fig. 3 and 4 is as follows:

Node M: L=75%, P=25%, D=100%, TP=100%

Node I:L=30%, P=75%, D=45%, TP=45%

Node C:L=80%, P=15%, D=100%, TP=100%

Node G:L=50%, P=30%, D=65%, TP=70%

The node S routing table of the value that obtains based on neighbor micronic dust from it can for:

Table 1

Adjacent node	Priority (" 1 " is for the highest)
Adjacent node	Priority (" 1 " is for the highest)	Node M node C node I node G	1 2 3 4

" pre-active heartbeat " algorithm can require micronic dust to refresh their routing table (for example every several milliseconds or a few microsecond, depending on environment requirement) with preset frequency.This required " heartbeat inspection " can relate to and depend on the data sampling rate of transducer.If contiguous micronic dust has fault, each micronic dust can be reduced the number of the tabulation of its path that returns end points, that is to say that if contiguous micronic dust has fault, those micronic dusts that use this out of order micronic dust to return end points should be deleted out of order micronic dust from their available micronic dust/path tabulation.

Under the situation of bust (having many micronic dusts all can not work), might some data can not return end points, yet this design has built-in redundancy, under the situation of bust, the transfer of data fault is reduced to minimum.

Initialization with upgrade whole virtual route path and when being connected, each interior node of environment all will be up to its fast and the most most effective path with the data back end points.Because the initialization mode of system, each micronic dust will be stored at least one path that returns end points.

Fig. 4 there is shown an illustrative path that data is sent to nodes X from node A again.When node A divides into groups its sampled data to send to Node B, suppose that Node B provides best connecting path according to the routing table of node A, must set up to shake hands to be received fully with authentication data.Do not shake hands if set up, node A just must send the suboptimum available communication path of its data again with reference to its routing table with searching.Notice that routing table (depending on refresh rate) may be identical, thereby node A will send it by connecting as another optimal node that backs up path.Notice that algorithm can make node A retry that its packet is sent to the Node B several times, seek another node that it can send to packet up to the routing table that it is created according to it.

Another feature of " pre-active heartbeat " is that each micronic dust can be analyzed certainly by checking following various function executing:

1. power supply state (p)

2. radio state (r)

3. transmit status (data transfer rate of being supported) (tx)

4. memory state (space) (m)

Sensor states (whether working) (s (1) ..., s (n) depends on " n " the individual transducer that is attached thereto)

For example, Node B can be carried out from analyzing with following result:

Table 2

The Node B function	State
The Node B function	State	Power supply state radio state transmit status memory status sensor state	50％ 75％ 40％ 10％ 100％

Depend on the minimum requirements of all functions, can require Node B to broadcast it and be in Passive Mode to its neighbor micronic dust, up to its some functional rehabilitations to predetermined Status Level, for example its memory state bring up to 50% and power supply state bring up at 75% o'clock.When reaching predetermined Status Level, Node B can forward aggressive mode to, upgrades its ability to neighbor micronic dust.

Notice that when a micronic dust was in " passive " pattern, this micronic dust can still can arrive another micronic dust with data relaying (playing a part bridge).The micronic dust that is in Passive Mode can play sign, does not attempt it as communication route (opposite with the micronic dust that is in aggressive mode) to warn other micronic dusts.In addition, the micronic dust that is in Passive Mode owing to the sensor states and the radio state of micronic dust can be used as to the replacement of main monitoring station or repairs the alert notice of this micronic dust.

Be appreciated that illustrated system, function, mechanism, method, engine and module can use the combination of hardware, software or hardware and software to realize here.They can be realized with computer system or other equipment that is fit to the illustrated method of execution here of any kind.The typical combination of hardware and software can be general-purpose computing system and control this computer system make it be implemented in the computer program of method described herein when this computer system of packing into is carried out.Perhaps, also can be with the special-purpose computer that the specialized hardware of carrying out one or more functional tasks of the present invention is housed.In another embodiment, the present invention partly or entirely can for example realize on a network such as the Internet with distribution mode.

The present invention can also be presented as a kind of computer program, and this computer program comprises that all can be implemented in method described herein and function, and can carry out these methods and function when packing a computer system into.Term such as computer program, software program, program, program product, software means in given context with any expression to one group of instruction of any language, code or symbol, and this group instruction can be directly or is transformed into another kind of language, code or symbol and/or (b) makes the specific function of system's execution with information processing capability after reproducing with different entity forms at (a).

For the purpose of illustration and explanation, more than provided explanation of the present invention.It is not an exhaustive, neither limit the invention to the definite form that is disclosed.Obviously, many remodeling and modification all are possible.Like this can be that conspicuous remodeling and modification all should be included in as within the scope of patent protection of the present invention that is provided by appended claims to the person skilled in the art.

Claims

1. wireless sensor network, described wireless sensor network comprises: a plurality of micronic dusts, each micronic dust have transducer and the wireless communication system of communicating by letter with neighbor micronic dust; Be distributed in the distributed routing table between each micronic dust in a plurality of micronic dusts; And the update system of regular update distributed routing table.

2. the wireless sensor network of claim 1, wherein each micronic dust also comprises solar cell.

3. the wireless sensor network of claim 1, wherein said communication system comprises Passive Mode and aggressive mode, described Passive Mode is used for data are relayed to the reception micronic dust from sending micronic dust, and described aggressive mode is used for sending the data that produced by micronic dust.

4. the wireless sensor network of claim 1, described wireless sensor network comprise that also at least one transmits router and a monitoring station.

5. the wireless sensor network of claim 1, wherein each micronic dust also comprises and adding and gathering system, allows this micronic dust to be collected into network and other micronic dusts are collected into network by neighbor micronic dust.

6. the wireless sensor network of claim 5, wherein each micronic dust storage is via the primary path of the neighbor micronic dust of collecting this micronic dust to end points.

7. the wireless sensor network of claim 6, wherein each micronic dust also comprises and is used to identify via the system of other neighbor micronic dust to one group of auxilliary path of end points.

8. the wireless sensor network of claim 7, wherein each micronic dust comprises the primary path that is arranged with end points and the routing table of one group of auxilliary path.

9. the wireless sensor network of claim 8, wherein each micronic dust is by analyzing its routing table of group communication criterion regular update of neighbor micronic dust.

10. a realization has the method for the wireless network of a plurality of equipment, and each equipment has the wireless communication system of communicating by letter with neighbouring device, and described method comprises the following steps: to add order and collect order from end points broadcasting from each device broadcasts; Utilize end points to make the equipment adjacent add network with end points; Collect signal from each device broadcasts that adds end points, so that other equipment add network; And from adding each other device broadcasts collection signal of network, so that more other equipment add networks.

11. the method for claim 10, described method also comprises step: repeat previous broadcasting step, up to there not being more equipment can add network.

12. the method for claim 11, wherein said wireless network comprises wireless sensor network.

13. the method for claim 12, wherein each equipment is the micronic dust with transducer and the wireless communication system of communicating by letter with neighbor micronic dust.

14. the method for claim 13, described method also are included in the step that each micronic dust stored is returned the primary path of end points.

15. also comprising by attempting communicating by letter with other neighbor micronic dust, the method for claim 14, described method make each micronic dust sign return one group of step of assisting path of end points.

16. the method for claim 15, described method also comprise the step that makes each micronic dust arrange primary path and one group of auxilliary path in routing table.

17. the method for claim 16, described method also comprise the step that makes each its routing table of micronic dust regular update by a group communication criterion of analyzing neighbor micronic dust.

18. a micronic dust that is used for sensor network, described micronic dust comprises: the transducer of sensitive context data; The communication system of communicating by letter with neighbor micronic dust; Micronic dust is built up in adding and gathering system in the mote network; The routing table of one group of path of end points is returned in arrangement from micronic dust; And the update system of regular update routing table.

19. the micronic dust of claim 18, described micronic dust also comprises solar cell.

20. the micronic dust of claim 18, wherein said communication system comprises Passive Mode and aggressive mode, and described Passive Mode is used for data are relayed to the reception micronic dust from sending micronic dust, and described aggressive mode is used for sending the data that produced by micronic dust.

21. the micronic dust of claim 18, wherein each micronic dust storage is via the primary path of the neighbor micronic dust of collecting micronic dust to end points.

22. the micronic dust of claim 21, wherein each micronic dust also comprises and is used to identify through the system of other neighbor micronic dust to one group of auxilliary path of end points.

23. the micronic dust of claim 18, wherein said update system is by analyzing its routing table of group communication criterion regular update of neighbor micronic dust.

24. the micronic dust of claim 18, wherein each micronic dust also comprise each function criterion of checking micronic dust from analytical system.